A getter material is useful for removing various reactive gases in vacuum systems. Palladium oxide(PdO), for example, can be placed within a vacuum space or enclosure to remove hydrogen which is released from the metal components in the vacuum space or enclosure. Initially, the hydrogen reacts with palladium oxide(PdO) to form water which is subsequently removed with molecular sieves in the vacuum space or enclosure. The reaction between palladium oxide(PdO) and hydrogen may be characterized by the following equation: EQU PdO+H.sub.2 .fwdarw.Pd+H.sub.2 O
Once palladium oxide(PdO) is reduced to form palladium metal(Pd), additional hydrogen is removed through using its surface, i.e., chemisorbing hydrogen on its surface.
Employing the getter material, such as palladium oxide, in vacuum insulated equipment, particularly those which are used for handling liquified or low temperature gases, e.g., liquid oxygen, however, can be problematic. If pure oxygen is rapidly introduced into the vacuum space or enclosure via an inner line weld failure, a container weld failure, a neck tube failure or any other structure failures, palladium oxide which has been reduced and has chemisorbed hydrogen on its surface will react with oxygen to generate a temperature up to about 1600 F. This high temperature can melt and ignite an insulation, such as aluminum foil insulation, which is normally used in the vacuum insulated equipment. Once the aluminum foil insulation is ignited, it will burn rapidly resulting in a large energy release which can violently rupture the outer vacuum jacket of the vacuum insulated equipment.
In order to prevent the getter material, such as palladium oxide, from igniting the aluminum insulation, it is packaged before it is employed in the vacuum insulated equipment. Packaging includes placing about 0.5 to about 2 grams of palladium oxide on a piece of a glass paper, folding the glass paper to form a rectangular packet, placing the rectangular glass packet on about 100 mesh copper screen and folding the copper screen over the rectangular glass packet to completely enclose the glass packet. The glass paper and copper screen combine to keep palladium oxide powder within the packet. Also, the copper screen serves as a heat sink to limit the outer surface temperature of the packet in the case of a sudden in-rush of oxygen. Even though the ignition of the insulation can be inhibited or prevented by the above packaging, the structure of the packet or package is susceptible to damage under rough handling conditions. In other words, the glass paper packet can be ripped under rough handling conditions, e.g., creased or unfolded during its installation into the vacuum space or folded incorrectly during fabrication, to release palladium powder therein. The released palladium powder could come into contact with the insulation and may ignite the insulation and rupture the outer vacuum jacket of the vacuum insulated equipment.
Thus, there is a genuine need in the art for a getter containment device which is not susceptible to damage and is useful for employing in vacuum systems.